1. Field of the Invention
The present invention relates to a method and apparatus for compacting plastic containers and other resilient structures, and more particularly to a means for compressing the walls of plastic containers and for embossing interlocking plastic tabs in adjoining walls so that the container remains compressed despite a tendency to regain its original shape.
2. Description of the Background
The importance of recycling has moved to the forefront of public awareness, and a great demand has arisen for new and improved methods and devices for recycling waste. Plastic is a significant waste product, making up about eighteen percent (18%) (by volume) of the solid waste stream. The per-unit value of plastic is high enough to warrant a considerable effort at separating plastic containers from the waste stream and recycling them. However, the amount of recyclable plastic per unit of waste is relatively low, owing to the large volume that hollow plastic containers normally occupy. The economics of recycling plastic containers suffers as a result because enormous amounts of storage and transportation space is required for relatively little plastic. Thus, the yield of recycled plastic often fails to justify the inventory and transportation costs. Conventional methods exist for reducing the volume of such plastic containers. For instance, containers may be delivered to reprocessing plants which chip or shread the containers prior to recycling. Alternatively, machinery is available to compact and bail the plastic containers for more efficient storage and transportation. These high volume means for densifying plastic containers successfully reduce the volume of the plastic containers by 12 to 15 times. However, such machinery is extremely expensive and can only be justified at a high volume recycling center. Consumer and other low cost densifiers have been made available for low volume use, but these typically only reduce the volume of plastic containers by about 2 to 3 times. This is because each molded plastic container retains a "memory" of its previous shape and the resiliency of the plastic causes the container to expand to its original shape after having been compressed. The low volume compactors only superficially compress plastic containers, and the economics of recycling is not significantly improved. It would be greatly advantageous to find an inexpensive means for permanently compressing such plastic containers so that they retain a maximum density during shipping and transportation.
Other well-known means currently exist for improving the rigidity of containers in general. Notably, U.S. Pat. No. 1,076,897 discloses a fastener adopted to rigidly secure the flaps of a box in order to prevent the flaps from unfolding. The disclosed box fastener is in the general shape of a triangle mounted on a short stem. The triangle can be wedged between the flaps of the box until the flaps clear the triangle section and become locked against the stem. The disclosed box fastener is metallic and can be bent to conform to the top of the box. This and similar teachings can be expanded for the development of an improved compactor for plastic containers which suppresses the resilient memory of the plastic containers such that they retain their shape when compacted.